The techniques of isolated intact adrenal cells and also superfusion have been applied to the study of stimulation and inhibition of steroidogenesis in the rat and bovine adrenal gland. The stimulating agents used have included ACTH, dibutyryl cyclic AMP, serotinin, prostaglandin PGE2, under ranging conditions of Ca ions concentrations and EDTA. The production of cAMP and cGMP by radio immunoassay and steroidogenesis by fluorescence has been measured in male and female rat adrenal tissue. Inhibitory agents including cyclohexamide SU-4885, 2,3- cyanoketone and glutethimide also are being studied in these preparations. For the direct measure of side-chain cleavage of cholesterol, an acetone powder preparation of bovine adrenal mitochondria is used and from this preparation a stimulatory factor for the side chain cleavage has been obtained. Purification of the soluble factor using Sephadex and DEAE cellulose strongly suggests a protein (mol. wt. 16,000) which is related to, or is present with adrenodoxin, since there is a 50 x enhancement of iron content. A similar activator has been isolated from the supernatant fraction of corpus luteum. We have previously shown, in collaboration with the laboratory of Dr. M. Dempsey that the liver-SCP (soluble carrier protein), which enhances cholesterol synthesis also stimulates cholesterol side-chain cleavage and that a cholesterol synthesizing SCP factor is present in the adrenal. One research objective is to demonstrate that cholesterol, available in several metabolic pools in the adrenal, is transported to the mitochondria linked with lipoprotein, which could be an adrenal soluble protein SCP, a mitochondria lipo protein or other LDLP-like factor which prevents cholesterol aggregation and enhances binding to the adrenal cytochrome P450 system. Pregnenolone formation under non- stimulated basal conditions and in the presence of ACTH has been compared.